The invention relates to a circuit arrangement for the control of the gear change points of the transmission stages of an automatic transmission, such as that of a vehicle, in dependence upon the speed of the vehicle and the position of the accelerator pedal.
With known arrangements the regulating element for the transmission stages is connected to the output of a circuit for measuring the speed of the vehicle, for instance by means of an additional transistor, to the collector of which a regulating element is connected and whereby the amplitude of a DC voltage is reduced. The regulating element can be connected to a filter, where it directly controls a DC voltage supply to inputs of logic circuits for the individual stages of a transmission. There are also known circuit arrangements wherein a change of a resistance, which together with a condenser determins the time constant of a monostable circuit, it is provided with an additional transistor connected as a variable resistance.
A drawback of the above-mentioned systems is that they are complicated. A reduction of the voltage supplied to the input of logic circuits is not advantageous since it results in a reduction of the sensitivity of these circuits. The circuit arrangement for the regulation of the time constant of the monostable circuit by an additional transistor is very much dependent on variations of the ambient temperature.